The overall objectives of this study are to explore systematically with quantitative methods the functional organization of prevertebral ganglia, the occurrence of afferent synaptic input to these ganglia from different functional activity by these ganglia. The areas of particular interest are: 1) the electrophysiological membrane properties of prevertebral neurons, 2) the synaptic responses, preganglionic pathways and patterns of innervation of single prevertebral neurons, 3) to determine if mechanoreceptors in the wall of the antrum, small bowel and large bowel make synaptic contact with prevertebral neurons and if so 4) to determine if these afferent fibers and the efferent noradrenergic neurons of the prevertebral ganglia constitute a peripheral reflex feed back loop controlling and regulating gastrointestinal motor activity. The method of approach will be the measurement in vitro of membrane properties and synaptic responses of single neurons using the intracellular recording technique. The prevertebral ganglia which will be studied are in the guinea pig the inferior mesenteric and celiac ganglia and in the cat the pelvic plexus, inferior mesenteric ganglion and solar plexus.